Byung-Ki Na

Effect of Electrical Pulse Forms on the CO2 Reforming of Methane Using Atmospheric Dielectric Barrier Discharge

Methane conversion using an electric discharge has been studied for many years. Recently, many research groups have developed high-frequency pulsed plasma reaction for methane conversion to higher hydrocarbons and synthesis gas. CO2 reforming of methane to synthesis gas has also attracted considerable interest as a method of utilization of the greenhouse gases, CO2 and CH4, which occupy most of man-made greenhouse gases. In this study, the influence of pulse form of applied voltage on methane and carbon dioxide conversions and product selectivity has been investigated using a cylindrical type DBD reactor. For this purpose, two kinds of power supply were compared, that is, AC power supply which has a high-frequency sinusoidal wave form, and AC pulse power supply which has modified AC pulse wave form. The conversions of methane and carbon dioxide were enhanced using pulsed plasma. The lower pulse width was more profitable economically.

Effects of oxidized biodiesel on formation of particulate matter and NO x from diesel engine

A test was conducted to investigate the effect of pure biodiesel without additives on formation of particulate matter (PM) and nitrogen oxide (NOx) in the exhaust gas of a diesel engine. Pure biodiesel from waste cooking oil without adding any additive was used. The biodiesel was oxidized at 110 °C for 10 days and blended with commercial automobile diesel oil distributed in the market as a testing fuel. Blended fuels were produced by adding 10% of oxidized biodiesel and un-oxidized biodiesel to automobile diesel oil, respectively. Material properties such as density, kinematic viscosity, oxidation stability, and cetane number were tested. Emission tests were conducted using a large diesel engine of direct injection type, inline six-cylinder, 4 stroke, turbocharger and intercooler. The oxidized and unoxidized biodiesel blends did not show any difference in density and kinematic viscosity. The oxidation stability of the oxidized biodiesel blends was lower than that of the unoxidized biodiesel blends. In the emission test, the two blends showed almost no difference in the total number of concentration of the micro-particles, and also showed almost no difference in particle size distribution such as nucleation mode and accumulation mode. On the other hand, the oxidized biodiesel blends showed less PM and NOx emission than the unoxidized biodiesel blends.

Study and characterization of W/Si and W/B4C multilayer for applications in hard X-rays mirror

Multilayer thin films with 2.3 nm-7.6 nm of d-spacing were deposited on fusion glass and float glass substrates by magnetron sputtering. Multilayer thin film with a lower interface roughness was deposited at an abnormal discharge region of I-V characteristic curve in DC glow discharge, compared to normal discharge region. Interface roughness of periodical multilayer in general depends on layer thickness, but in this study interface roughness was controlled by adjusting deposition conditions regardless of layer thickness. But interface roughness and X-ray reflectivity (XRR) of multilayer react sensitively to surface roughness of substrate. Multilayer thin film with 2.3 nm d-spacing shoes 42% of characteristic X-ray reflectivity(Cu Kα, λ=∼0.154 nm), while 3.6 nm d-spacing shows 80% of reflectivity. XRR, transmission electron microscope (TEM) and atomic force microscopy (AFM) were used to analyze the interface roughness (σ), surface roughness and d-spacing.

A study on Property of Emission Gas by the Content Variation of Urea

Abstract - National and international regulations on the exhaust gases of diesel engines are being strengthened, and a study of the combutsion engine and the post-porcessing system are in progress as a variety of ways. There are many techniques for the removal of nitrogen oxide like HC-SCR, LNT, Urea-SCR. And the technical development on the Urea-SCR owing to high conversion efficiency and fuel economy characteristics has being processed. This study investigated the physical/chemical properties of urea according to the change of the urea content, and were analysed the characteristic of exhaust gas. According to the increase of urea content, the contests of biuret aldehyde, phosphate content was increased and the changes of emission quantity of carbon monoxide, hydrocarbons and particulate matter in the exhaust gas was very slight. The emission quantity of NOx was decreased in accordance with increasing the urea content and it was shown to be more than 80 % in the urea solution having more than 30 wt%.

The Study for Effect of Biodiesel Antioxidants on Properties and Emissions

Biodiesel as alternative fuels has been widely studied due to biodiesel merits such as lower sulfur, lower aromatic hydrocarbon and higher oxygen content. But biodiesels could be easily oxidized by several conditions. In this study, various antioxidants such as propyl gallate, TBHA, TBHQ, DTBHQ, butyl-amin, aniline and pyrogallol were added in the biodiesel produced by the used cooking oil, then the material property test and the vehicle emissions test were conducted in accordance with test method. From the results of material property test, all antioxidants were suitable for the quality standard of density and kinematic viscosity, but Propyl gallate and Pyrogallol, as a type of Gallate additives, showed that the result of TAN increased rapidly according to the increase of the amount of additives. In the oxidation stability test, TBHQ, Butyl-amine and Aniline showed the excellent oxidation stability. Also, when considering the material property test, TBHQ was verified to the most excellent additives. In case of the vehicle emissions test, the testing was conducted by using the biodiesel added by TBHQ and was conducted by using two light duty diesel vehicles suitable for the EURO 4 and EURO 5 emission regulation. The result of testing showed that when the TBHQ was added, the amounts of CO, NOx and NMHC+NOx were decreased but the amount of was increased.

A study on the evaluation of metal component in automatic transmission fluid by vehicle driving

요약 자동변속기유는 자동차의 자동변속기의 성능을 유지시키기 위해 사용되는 유체이다최근 자동차 제조. 사에서는 일반적으로 자동변속기유를 주행후 교환 또는 무교환을 보증하고 있지만 국내에80000~100000 km 서는 많은 운전자들이 이하에서도 자동변속기유를 교환하고 있는 것으로 조사되었다빈번한 50000 km . 자동변속기유의 교환은 환경오염과 차량유지비용을 상승시키는 원인으로 작용되고 있다 . 본 연구에서는 사용하지 않은 신유와 와 를 각각 주행한 뒤 회수된 자동변속기유를 50000 km 100000 km대상으로 인화점연소점유동점동점도저온겉보기점도전산가금속분과 같은 물리적 특성을 분석하였, , , , , , 다연구결과신유에 비해 사용유는 전산가유동점금속분이 증가되는 것을 확인하였지만두 종류의 사용. , , , , 유 의 물리적 특성과 금속분 함량의 차이는 크지 않음을 알수 있었다(50000 km, 100000 km) . : , , , , , 주요어 자동변속기유교환주기유도결합플라즈마신유사용유금속분Abstract - Automatic transmission fluid (ATF) is used for automatic transmissions in the vehicle as the characterized fluid. Recently, the vehicle manufacture usually guarantee for fluid change over 80000~100000 km mileage or no exchange, but most drivers usually change ATF below every 50000 km driving in Republic of Korea. It can cause to raise environmental contamination by used ATF and increase the cost of driving by frequently ATF change.In this study, we investigate the various physical properties such as flash point, fire point, pour point, kinematic viscosity, cold cranking simulator, total acid number, and metal component concentration for fresh and used ATF after driving (50000 km, 100000 km). The result showed that the total acid number, pour point, Fe, Al and Cu component had increased than fresh ATF, but 2 kind of used oil (50000 km and 100000km) had similar physical values and metal component concentration

A study on Property and CO 2 Emission Factor of Domestic Transportation Fuel

Intergovernmental Panel on Climate Change(IPCC) suggested the three methodology, Tier 1/2/3, considering with the accuracy and difficulty of greenhouse gas emission statistics according to the report determined as the international criterion. In Korea, the existing inventory building was made by the Top-down approach applying with the emission factors for transportation in the entire energy consumption, the emission factors were investigated under the domestic traffic situation which did not reflect by the continuing increase of vehicle and the change of road section. From the suggestion of IPCC, which it is estimated that the emission estimation of CO 2 in greenhouse gas emission could be calculated more accurate by the carbon content according to the fuel, the establishment of measures to respond to climate change from the latest greenhouse gas emissions statistics will be able to improve the accuracy of national statistics using monthly or seasonally the analysis of carbon content about the transportation fuels.